Seat belt with an automatic unlocking device

Abstract

A seat belt automatic unlocking device includes a seat belt having an end portion with a fitting, a lock box structure which receives the seat belt end portion, and a locking lever movably mounted on the lock box structure between a locked position and an unlocked position. The locking lever engages and locks the fitting when in the locked position, the locking lever disengaging and unlocking the fitting when in the unlocked position to thereby unlock the seat belt. A mounting structure is mounted on a vehicle on which the seat belt automatic unlocking device is used, and a connection connects the mounting structure to the lock box structure. A releasable device is operably connected between the mounting structure and the locking lever and operable between a release position and a non-release position, the releasable device being operable to move the locking lever to its unlocked position when the releaseable device is moved to its release position. The releasable device is movable to the released position when the mounting structure and the lock box structure are moved to a separated position, whereby the releasable device automatically unlocks the fitting to thereby unlock the seat belt after application of a separating force exceeding a predetermined biasing force.

I claim: 
     
       1. A seat belt automatic unlocking device comprising a seat belt having an end portion with a fitting, a lock box structure which receives said seat belt end portion, a locking lever movably mounted on said lock box structure between a locked position and an unlocked position, said locking lever engaging and locking said fitting when in said locked position, said locking lever disengaging and unlocking said fitting when in said unlocked position to thereby unlock said seat belt, a mounting structure mounted on a vehicle on which the seat belt automatic unlocking device is used, connecting means connecting said mounting structure to said lock box structure, and releasable means operably connected between said mounting structure and said locking lever and operable between a release position and a non-release position, said releasable means being operable to move said locking lever to its unlocked position when said releasable means is moved to its release position, said releasable means being operable to retain said locking lever in its locked position when said releasable means is in its non-release position, said releasable means comprising a rotatably mounted drum and a rotatably mounted pulley along with a rope means extending between said drum and said pulley, said pulley being rotatable by said rope to a position to effect release of said locking lever to its unlocked position, said connecting means comprising biasing means biasingly maintaining a non-separated position between said mounting structure and said lock box structure, said biasing means permitting relative movement between said mounting structure and said lock box structure from said non-separated position to a separated position upon application of a separating force exceeding a predetermined biasing force to said biasing means, said releasable means being retained in said non-release position when said mounting structure and said lock box structure are in said non-separated position, said releasable means being moved to said released position when said mounting structure and said lock box structure are moved to said separated position, whereby said releasable means automatically unlocks said fitting to thereby unlock said seat belt after application of said separating force exceeding said predetermined biasing force. 
     
     
       2. A seat belt automatic unlocking device according to claim 1, wherein said connecting means comprises a connecting bolt passing through bolt openings in said mounting structure and said lock box structure, at least one of said openings being elongated to permit relative transverse sliding between said one opening and said bolt to permit said relative movement between said mounting structure and said lock box structure between said separated and non-separated positions. 
     
     
       3. A seat belt automatic unlocking device according to claim 1, wherein said rope means is wound around said drum, said releasable means further comprising brake means operable to engage said drum to prevent rotation of said drum, said releasable means further comprising a pivotal brake lever pivotably mounted on said lock box structure and an engagable part mounted on said mounting structure, said engagable part engaging said pivotal brake lever when said mounting structure and said lock box structure are in said non-separated position, said engagable part disengaging from said pivotal brake lever when said mounting structure and said locking structure are in their separated position, said brake lever releasing said brake means when said brake lever is disengaged by said engagable part. 
     
     
       4. A seat belt automatic unlocking device according to claim 1, wherein said releasable means further comprises rotary means rotatably supporting said pulley on said lock box structure, said releasable means further comprising an actuating lever operable to effect movement of said locking lever between its locked and unlocked positions, said actuating lever being actuated by said rotary means. 
     
     
       5. A seat belt automatic unlocking device according to claim 4, wherein said rotary means comprises a disc having a notch, said actuating lever being movable between an actuated position in which said actuating lever engages said notch and an unactuated position in which said actuating lever is disengaged from said notch. 
     
     
       6. A seat belt automatic unlocking device according to claim 5 further comprising biasing means biasing said actuating lever toward said actuated position. 
     
     
       7. A seat belt automatic unlocking device according to claim 6 further comprising spring means biasing said locking lever towardsd its locked position.